Circuit Design And Research Of Broad-Spectrum Imaging System

Broad-spectrum imaging technology from visible light to short-wave infrared has advantages such as obtaining a lot of information,wide application scenarios,strong anti-interference capability,and all-weather imaging,and plays an important role in many fields such as national defense construction,industrial testing,and intelligent driving.However,currently,most broad-spectrum imaging systems are realized using indium gallium arsenide detectors or dual-camera fusion methods,which can lead to problems such as high imaging circuit costs and large volume.Therefore,designing a low-cost broad-spectrum imaging circuit that can detect on a single chip is of great significance for the above problems.Firstly,the colloid quantum dot detector,which has the advantages of low preparation cost,simple process,and wide spectral imaging,was selected as the core of the system.A low-cost,highly portable,and scalable wide-spectrum imaging circuit hardware system was constructed by studying the imaging and readout characteristics of the detector.The scheme addresses the problems of large output signal noise,low quantum efficiency,and uneven response of the colloid quantum dot detector,proposing a method combining multi-stage filtering with high-impedance low-noise follower circuit,and combining programmable gain amplification with programmable bias voltage circuit,together with the FPGA main control circuit,to achieve signal amplification in different scenarios while reducing signal noise and improving the system signal-to-noise ratio.Secondly,to verify the accuracy of the proposed scheme,a signal preprocessing circuit was built based on the existing mass-produced chips and the constructed hardware architecture system.A 5th-order Butterworth differential low-pass filter was implemented,and multi-stage signal filtering was completed in conjunction with the front-end circuit.A programmable amplification circuit based on a separation device was designed to amplify the signal.An analog-to-digital and digital-to-analog conversion circuit based on the ADC12D040 and AD9708 chips was designed to digitize the signal.An HDMI interface communication circuit and a digital signal processing circuit based on ZYNQ as the core were designed to achieve digital signal processing and transmission.Using hardware description language,the digital logic driving of each module was designed,and the simulation of each module and overall function was completed,achieving system layout wiring,timing constraints,and power consumption control.Finally,the simulated output signal of the colloidal quantum dot broad-spectrum image sensor was tested using hardware circuit testing equipment to complete module and systematic testing.The test results show that the broad-spectrum imaging system circuit constructed in this article can serve as the back-end imaging circuit of broad-spectrum quantum dot detectors,with a response band of 0.4～2.5 μm.By calculation,the maximum signal gain can be achieved as 20 d B,the out-of-band signal attenuation is 100 dB,the cutoff frequency is 16 MHz,the signal acquisition rate is 40 MHz,and the transmission rate is 30 frames.At the same time,the imaging circuit structure constructed in this article and the method of signal processing can also provide a convenient reference for the development of array imaging system circuits for subsequent quantum dot photosensitive materials or other similar materials.